There is only one filter & you already found that. The smell is due to bacterial growth in the tub & it is caused by eco friendly detergents/fabric softeners & low wash temp. Run a 90C program once a month & add a small dose of chlorine (bleach). Clean the door bellow with bleach/hot water mixture as well. There are also a few off the shelf products you can use, check out your local supermarket. In my experience a high temp maintenence with a little bleach works just as well...and its cheaper.
Mike
October 2009